Describe the bug
Discussed today in the maintainers meeting with @carolromero and she mentioned there are some weird behavior with the digest notification emails being sent by MetaDecidim which is currently running 0.27.0.rc1 at the time of reporting this.

The weird behavior includes:

• Notifications from the DecidimFest conference space are not being included in the digest email, we discussed this may be related to following the conference space but we are unsure if you can even follow a conference space at the moment
• Getting today's notification included in the yesterday's digest

The working behavior includes:

• Getting notifications about admin related events, such as a new user group was added
• Getting notifications about things that the user is following, such as their own proposals or proposals have followed

To Reproduce
This requires some investigation and I just create this issue to track it.

Expected behavior

• Get every notification included in the digest email that the user wants to receive.
• Get notifications according to the desired schedule, i.e. don't include today's notifications in the yesterday's digest

Screenshots
N/A

Stacktrace
N/A

Extra data (please complete the following information):

• Device: (any)
• Device OS: (any)
• Browser: (any)
• Decidim Version: 0.27.0.rc1
• Decidim installation: MetaDecidim

Additional context
N/A